1. Field of the Invention
The present invention relates to a cartridge locking mechanism for locking a magnetic tape cartridge in a magnetic tape apparatus.
2. Description of the Related Art
In a magnetic tape apparatus, when a cartridge is inserted into a cartridge tray, it is necessary to lock the cartridge so that it may not come out of the cartridge tray, but when the cartridge is to be removed, it is necessary to unlock the cartridge so that the cartridge can be removed smoothly. It is demanded that a cartridge locking mechanism satisfy the two requirements just described.
A cartridge locking mechanism of the type described is disclosed in Japanese Patent Laid-Open No. 2001-118305. The cartridge locking mechanism is shown in FIGS. 15(a), 15(b), 16, 17(a) and 17(b).
Referring to FIGS. 15(a) to 17(b), the cartridge locking mechanism shown is so structured that it locks one of the opposite left and right sides of a cartridge and includes a locking lever 19 supported for pivotal motion by a vertical pin 20-1 only on the right side face of a cartridge tray 20 into which a cartridge 1 is inserted. A hooked portion 19-1 shown in FIG. 16 is provided at a tip end of the locking lever 19 such that it projects toward the cartridge tray 20 side, and first and second inclined faces 19-2 and 19-3 are formed on the opposite side faces of a tip end projection which projects downwardly from the hooked portion 19-1.
As particularly seen in FIG. 15(b), a tension spring 21 extends between a spring anchoring pin 19-4 extending vertically from a lower end of the locking lever 19 and a spring anchoring pin 20-2 extending vertically from the rear face side of the cartridge tray 20 so that torque toward the inner side of the cartridge tray 20 is applied to the locking lever 19 from the tension spring 21.
In a standby state before the cartridge 1 is inserted into the cartridge tray 20, the second inclined face 19-3 of the locking lever 19 engages with a locking pin 22 formed in a projecting manner on a base not shown of the cartridge tray 20 as seen in FIG. 15(b) so that the locking lever 19 is held in an unlocking state wherein it does not lock the cartridge 1.
If the cartridge 1 is inserted into the magnetic tape apparatus, then the cartridge tray 20 is pushed in together with the cartridge 1, whereupon the locking lever 19 and the cartridge tray 20 are placed into a demounted positional relationship as seen in FIG. 17(b) wherein the hooked portion 19-1 of the locking lever 19 is fitted in a locking hole 1-1 formed on a side face of the cartridge 1 to lock the cartridge 1. In this instance, since the biasing force acting in the direction indicated by an arrow mark F in FIG. 17(b) is applied to the cartridge tray 20, the locking lever 19 is restricted by the locking pin 22 and keeps its locking state.
If the cartridge 1 is pulled off from the cartridge tray 20 in the state illustrated in FIGS. 17(a) and 17(b), then the locking lever 19 is pulled off together with the cartridge 1. Also in this instance, since the cartridge tray 20 is biased in the direction indicated by the arrow mark F in FIG. 17(b) by the above-mentioned spring not shown, the engaging position between the tip end of the locking lever 19 and the locking pin 22 changes from the first inclined face 19-2 to the second inclined face 19-3, whereupon the locking lever 19 is pushed open to unlock the cartridge 1.
With the cartridge locking mechanism described above, however, particularly where an automatic loader is used to load and unload a medium, when the cartridge is removed by means of a picker, high pulling out force is sometimes required and therefore the cartridge cannot be removed because of insufficient pulling out force.
In particular, since the cartridge locking mechanism locks only one side of the cartridge 1, when the cartridge 1 is to be pulled off, a moment acts around the hooked portion 19-1 of the locking lever 19 and varies the pulling out force of the cartridge 1. Further, if the first inclined face 19-2 of the locking lever 19 is disengaged from the locking pin 22 by an impact or the like to cancel the lock inadvertently, then the cartridge 1 may possibly be ejected from the cartridge tray 20.